1. Field
Embodiments relate to an image-resolution-improvement apparatus and method, and, more particularly, to an image-resolution-improvement apparatus and method which can increase the resolution of an input image at a high magnification to thereby obtain a high-quality final image.
2. Description of the Related Art
Image resolution improvement technology may be broadly classified into a method of using linear filtering and a method of using non-linear filtering.
Linear filtering methods include methods of converting image resolution using linear filtering techniques such as bilinear interpolation and cubic interpolation. When linear filtering technology is used, high-frequency components of an input image are insufficiently reproduced in a resolution expansion process. Consequently, the definition, i.e., quality, of a final image is significantly undermined. In order to address this problem, a technology for outputting a high-definition signal has been suggested. The suggested technology applies peaking to a low-resolution signal to identify potential edge pixels, up-converts a peaked video signal, and outputs a high-definition signal by sequentially performing edge pixel detection, edge linking and luminance transient improvement. However, the suggested technology requires a large amount of computation and a complicated hardware structure.
Non-linear filtering technology can be divided into a directional interpolation method and a content-based interpolation method. The directional interpolation method performs interpolation using edge information of an image in a direction parallel to an edge direction, thereby preventing blurring of edge components. The content-based interpolation method calculates optimized scaling filter coefficients in a prior learning process, and performs resolution conversion by selecting a learned filter coefficient according to the local characteristics of an input image. While the above methods show relatively favorable results in the edge region of an image, it is difficult to expect high image quality in the fine texture regions of the image.